Confirming that the Hezbollah message had been passed on by the UN force, Unifil, Mr Yaalon added:
"I can't say whether the events are behind us.
"Until the area completely calms down, the Israel Defense Forces will remain prepared and ready."
Wednesday's cross-border violence erupted when Israeli military vehicles were struck by anti-tank missiles near Mt Dov, in the Shebaa Farms area, a tract of land where the borders of Israel, Lebanon and Syria meet.
Hezbollah said it was retaliation for an Israeli air strike that killed six of its fighters and an Iranian Revolutionary Guards general in the Syrian Golan Heights 10 days ago.
The UN Security Council is to discuss the fighting at an emergency meeting called by France in New York.
A senior UN official on the ground in Lebanon urged "maximum restraint to prevent an escalation".
Israeli Prime Minister Benjamin Netanyahu held an emergency security meeting and said the attackers would "pay the full price".
What are the Shebaa Farms?
- The farms cover an area about 14km (9 miles) long and 2.5km wide, to the south of the Lebanese village of Shebaa, on the western slopes of Mount Hermon/Jabal al-Sheikh
- The area has been a flashpoint for violence since Israeli forces withdrew from Lebanon in 2000
- Until the 1967 Middle East war, the farms were under Syrian control, but the farmers had Lebanese citizenship
- The area was captured by Israel and annexed in 1981 along with the rest of the Golan Heights, a move not internationally recognised
- The Lebanese government says the farms are part of its territory, a claim backed by Damascus, but not the UN
- Hezbollah has consistently used Israel's presence in the area as justification for retaining its weapons and continuing "resistance"
- BBC